To become adult comprehenders of language, children must develop rapid access to the meanings of words. Central to adult sentence processing are the so-called semantic restrictions of verbs. The subject of a sentence must be capable performing the action denoted by the verb, while the direct object must be the sort of thing that can be sensed, manipulated, or changed in the relevant way. Because previous methods have required comprehenders to read, nothing at all is yet known about when children develop rapid access to these restrictions. Development of this capacity can now be studied with the newly developed head- mounted eye-tracker, which allows rich interference to e made from the time-course and sequence of visual fixations. The proposed work will exploit the fact that many verbs place restrictions on the affordances of their direct objects-the actions made possible by their physical properties. Given the command to "Open the box," for instance, listeners who have rapid access to semantic restrictions should begin searching for an appropriate object (i.e., one with an unsealable interior volume) shortly after hearing the verb, listeners who do not have such access should begin searching only after hearing the direct object. Through studying how children of different ages perform in this task, a great deal will be learned about when learners approach maturity as rapid, efficient comprehenders of language.